Rollup merge of #87385 - Aaron1011:final-enable-semi, r=petrochenkov

Make `SEMICOLON_IN_EXPRESSIONS_FROM_MACROS` warn by default

This PR makes the `SEMICOLON_IN_EXPRESSIONS_FROM_MACROS` lint warn by default.

To avoid showing a large number of un-actionable warnings to users, we only enable the lint for macros defined in the same crate. This ensures that users will be able to fix the warning by simply removing a semicolon.

In the future, I'd like to enable this lint unconditionally, and eventually make it into a hard error in a future edition. This PR is a step towards that goal.

5 files changed, 45 insertions, 15 deletions

diff --git a/src/test/ui/lint/semicolon-in-expressions-from-macros/allow-semicolon-in-expressions-from-macros.rs b/src/test/ui/lint/semicolon-in-expressions-from-macros/allow-semicolon-in-expressions-from-macros.rs
deleted file mode 100644
index 6f9e6ec0a57..00000000000
--- a/src/test/ui/lint/semicolon-in-expressions-from-macros/allow-semicolon-in-expressions-from-macros.rs
+++ /dev/null
@@ -1,15 +0,0 @@
-// check-pass
-// Ensure that trailing semicolons are allowed by default
-
-macro_rules! foo {
-    () => {
-        true;
-    }
-}
-
-fn main() {
-    let val = match true {
-        true => false,
-        _ => foo!()
-    };
-}
diff --git a/src/test/ui/lint/semicolon-in-expressions-from-macros/auxiliary/foreign-crate.rs b/src/test/ui/lint/semicolon-in-expressions-from-macros/auxiliary/foreign-crate.rs
new file mode 100644
index 00000000000..781391cc574
--- /dev/null
+++ b/src/test/ui/lint/semicolon-in-expressions-from-macros/auxiliary/foreign-crate.rs
@@ -0,0 +1,4 @@
+#[macro_export]
+macro_rules! my_macro {
+    () => { true; }
+}
diff --git a/src/test/ui/lint/semicolon-in-expressions-from-macros/foreign-crate.rs b/src/test/ui/lint/semicolon-in-expressions-from-macros/foreign-crate.rs
new file mode 100644
index 00000000000..374506366f8
--- /dev/null
+++ b/src/test/ui/lint/semicolon-in-expressions-from-macros/foreign-crate.rs
@@ -0,0 +1,9 @@
+// aux-build:foreign-crate.rs
+// check-pass
+
+extern crate foreign_crate;
+
+// Test that we do not lint for a macro in a foreign crate
+fn main() {
+    let _ = foreign_crate::my_macro!();
+}
diff --git a/src/test/ui/lint/semicolon-in-expressions-from-macros/warn-semicolon-in-expressions-from-macros.rs b/src/test/ui/lint/semicolon-in-expressions-from-macros/warn-semicolon-in-expressions-from-macros.rs
new file mode 100644
index 00000000000..2c63311e659
--- /dev/null
+++ b/src/test/ui/lint/semicolon-in-expressions-from-macros/warn-semicolon-in-expressions-from-macros.rs
@@ -0,0 +1,16 @@
+// check-pass
+// Ensure that trailing semicolons cause warnings by default
+
+macro_rules! foo {
+    () => {
+        true; //~  WARN trailing semicolon in macro
+              //~| WARN this was previously
+    }
+}
+
+fn main() {
+    let _val = match true {
+        true => false,
+        _ => foo!()
+    };
+}
diff --git a/src/test/ui/lint/semicolon-in-expressions-from-macros/warn-semicolon-in-expressions-from-macros.stderr b/src/test/ui/lint/semicolon-in-expressions-from-macros/warn-semicolon-in-expressions-from-macros.stderr
new file mode 100644
index 00000000000..d770a8c8f36
--- /dev/null
+++ b/src/test/ui/lint/semicolon-in-expressions-from-macros/warn-semicolon-in-expressions-from-macros.stderr
@@ -0,0 +1,16 @@
+warning: trailing semicolon in macro used in expression position
+  --> $DIR/warn-semicolon-in-expressions-from-macros.rs:6:13
+   |
+LL |         true;
+   |             ^
+...
+LL |         _ => foo!()
+   |              ------ in this macro invocation
+   |
+   = note: `#[warn(semicolon_in_expressions_from_macros)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #79813 <https://github.com/rust-lang/rust/issues/79813>
+   = note: this warning originates in the macro `foo` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+warning: 1 warning emitted
+